Light-emitting device

Abstract

There is provided an organic light-emitting device obtained by using a specific copper coordination compound as a light-emitting material, which has a basic structure in which two copper ions are crosslinked in a ring form by one of atomic groups containing a halogen atom, a sulfur atom, and an nitrogen atom. The light-emitting device provides high luminescence efficiency and high stability at low cost by using an inexpensive copper coordination compound as a light-emitting material.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a light-emitting device using an organic compound. More specifically, the present invention relates to an organic light-emitting device using a metal coordination compound as a light-emitting material so as to allow high luminescence efficiency in a stable manner.

2. Related Background Art

An organic electroluminescence (EL) device has been extensively studied for its practical application as a light-emitting device with a high responsiveness and high luminescence efficiency (see, e.g., “Macromol. Symp.”, 125, pp. 1-48 (1997)).

A copper coordination compound can be produced at a comparatively low cost because of inexpensive raw materials. Thus, exploiting the characteristics of the copper coordination compound would lead to a high-performance organic EL device with low cost.

For instance, organic EL devices using copper complexes have been disclosed in Japanese Patent No. 2940514 B and Y. Ma et al., “High Luminescence Gold (1) and Copper (1) complexes with Triplet Excited State for Use in Light-Emitting Diodes”, Advanced Materials, 1999, 11, No. 10, p. 852. However, these EL devices are extremely poor in luminescence efficiency and described insufficiently in these documents in terms of their efficiency. The characteristics of the cooper coordination compound may be insufficiently brought out. Thus, the cooper coordination compound has insufficient property to be used for a display, illumination, or the like.

Furthermore, in “Chemical Review”, 1999, 99, p. 3625-3647 and the proceedings of “the 15th Photochemistry Panel Discussion of Coordination Compound” (Japan), 2001, p. 91, copper coordination compounds are disclosed. However, these documents describe only photoluminescence emitted in a solution or crystalline particle powder, while no luminescence of an organic EL device under excitation with an electric current is described.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a light-emitting device with high luminescence efficiency, high stability, and low cost using an inexpensive copper coordination compound.

An organic light-emitting device according to the present invention includes a copper coordination compound having a partial structural formula represented by the following general formula (1) as a light-emitting material:

##STR00001##
(In the formula (1), Cu represents a copper ion; X represents an atomic group containing a halogen, sulfur, or nitrogen atom; and at least one of A1 to A3 is a ligand composed of an atomic group containing a carbon atom and may be covalently bound to another one).

In the organic light-emitting device according to the present invention, a copper coordination compound is preferably used as a light-emitting material, which has a partial structural formula represented by one of the following general formulae (2) to (8) that contains the partial structure represented by the general formula (1):

##STR00002##
(In the formula (2), Cu represents a copper ion; X represents an atomic group containing a halogen, sulfur, or nitrogen atom; N represents a nitrogen atom of an imine group in a cyclic group; and at least one of A1 to A3 is a ligand composed of an atomic group containing a carbon atom and may be covalently bound to another one).

##STR00003##
(In the formula (3), Cu represents a copper ion; X represents an atomic group containing a halogen, sulfur, or nitrogen atom; P represents a phosphorus atom in a phosphine compound; R₁ to R₃ independently or identically represent a linear, branched, or cyclic alkyl group or an aromatic ring group which may have a substituent; and at least one of A1 to A3 is a ligand composed of an atomic group containing a carbon atom and may be covalently bound to another one).

##STR00004##
(In the formulae (4-1) to (4-5), Cu represents a copper ion; X represents an atomic group containing a halogen, sulfur, or nitrogen atom; and N—N, P—N, and P—P represent bidentate ligands in which each ligand has two coordinating atoms, where N—N contains two nitrogen atoms of an imine group, P—N contains one nitrogen atom of the imine group and one phosphorous atom, and P—P contains two phosphorous atoms).

##STR00005##
(In the formulae (5-1) to (5-3), Cu represents a copper ion; X represents a halogen atom; N represents a nitrogen atom in an imine group; P represents a phosphorus atom; N—N, P—N, and P—P represent multidentate ligands in which each ligand has two or more coordinating atoms, where N—N contains two nitrogen atoms of the imine group, P—N contains one nitrogen atom of the imine group and one phosphorous atom, and P—P contains two phosphorous atoms; and each of A1 and A2 represents a ligand composed of an atomic group containing a carbon atom).

##STR00006##
(In the formula (6), Cu represents a copper ion; X represents a halogen atom; and L¹ to L⁴ represent monodentate coordinated with a nitrogen atom or a phosphorus atom).

##STR00007##
(In the formula (7), Cu represents a copper ion; X represents a halogen atom; and N represents a nitrogen atom of an imine group in a cyclic group).

##STR00008##
(In the formula (8), Cu represents a copper ion; X represents a halogen atom; P represents a phosphorus atom in a phosphine compound; and R¹ to R³ independently or identically represent a linear, branched, or cyclic alkyl group or an aromatic ring group which may have a substituent).

Further, in the organic light-emitting device according to the present invention, the following structures are included as preferred modes:

the copper ion has a valence of +1;

the copper coordination compound is used as a light-emitting material, which has the partial structural formula represented by the general formula (1) is a high-molecular copper coordination compound that contains two or more of the partial structure formulae at regular intervals;

the copper coordination compound is used as a light-emitting material, which has the partial structural formula represented by the general formula (1) is a non-ionic copper coordination compound that is electrically neutral; and

• • the light-emitting layer contains a portion in which a content of the light-emitting material is 100%.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A, 1B, 1C and 1D are cross-sectional schematic diagrams that illustrate the configuration of a light-emitting device of the present invention;

FIGS. 2A, 2B and 2C show luminescence spectra of compounds synthesized in examples of the present invention;

FIG. 3 shows luminescence spectra with respect to the examples of the present invention; and

FIG. 4 shows a molecular structure as a result of the crystal analysis of the exemplified compound 1253.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

An organic light-emitting device of the present invention employs a copper coordination compound having a specific partial structural formula as a light-emitting material so that the organic light-emitting device can be cost-effectively provided with high luminescence efficiency and stable luminescence.

Hereinafter, the organic EL device of the present invention will be described in detail.

At first, the characteristics of a copper coordination compound (copper complex) as a light-emitting material of the present invention will bed described.

The copper coordination compound used in the present invention has a partial structural formula represented by the following general formula (1).

##STR00009##

In the formula (1), Cu represents a copper ion; X represents an atomic group containing a halogen, sulfur, or nitrogen atom; and at least one of A0 to A3 is a ligand composed of an atomic group containing a carbon atom and may be covalently bound to another one.

In other words, the copper coordination compound used in the present invention is a coordination compound having a cross-linked portion with two atomic groups each containing a halogen, sulfur, or nitrogen atom. A copper coordination compound cross-linked by a halogen atom is suited for a light-emitting material because of its thermal stability and high luminescence efficiency. Particularly in a solid powder state, the copper coordination compound cross-linked by a halogen atom characteristically shows higher luminescence efficiency than that of another compound. In addition, even if the copper coordination compound is cross-linked by a sulfur atom, the copper coordination compound shows high luminescence efficiency and excellent chemical stability. Besides, various kinds of copper coordination compounds may be designed by providing a ligand having a sulfur atom with any of various substituents. In general, most of compounds, which emit luminescence in their dilute solutions, generate extremely poor luminescence when they are in solid powder states. Those compounds form association products in the ground state or excited association products by the interaction between light-emitting material molecules, so that the natural luminescence properties of the compounds are no longer obtained. Such a phenomenon is known as a “concentration quenching”.

The copper coordination compound of the present invention can be a light-emitting material which is hardly subjected to the concentration quenching. Therefore, when a light-emitting layer in a light-emitting device is considered, the concentration quenching can be generally avoided by the addition of a small amount of a light-emitting material as a guest material to a host material. As the light-emitting material of the present invention is not subjected to the concentration quenching, the light-emitting layer may contain the light-emitting material in higher concentration or in 100% concentration. Therefore, the light-emitting device having high luminescence efficiency and improved productivity can be produced. In addition, the luminescence property of the light-emitting material of the present invention shows a small concentration dependence and retrains variations in production and so on. Also from this viewpoint, the light-emitting material of the present invention allows the production of a light-emitting device having high productivity.

A copper ion used as the central metal of the copper complex is preferably a positively charged monovalent copper ion. When the electron configuration of a copper atom is taken into consideration, the positively-charged monovalent copper ion contains 10 d-electrons. Generally, a transition metal having d-electrons in even number often shows good luminescence property.

The copper coordination compounds, which can be used in the present invention, are generally classified into a dimer type and a tetramer type. In addition, the dimer type is further classified into three different types 1 to 3 as follows.

##STR00010##

In the above formulae, Cu represents a copper atom and L¹ to L⁴ represents ligands, respectively, where the ligands are respectively monodentate ligands independent from each other or the ligands form a multidentate ligand in which two or more coordinating atoms are covalently bound together.

X in each of the above dimer types 1 and 2 represents an atomic group that contains a halogen, sulfur, or nitrogen atom. Two atoms or two atomic groups can cross-link a Cu atom. In addition, in the dimer type 1, a high-molecular coordination compound having any of these biding structural units can be formed. In this high-molecular copper coordination compound, X may be also an atomic group containing a halogen, sulfur, or nitrogen atom.

In addition, with respect to the above dimer type 3 and the tetramer type, X is a halogen atom. In the dimer type 3, an atomic group containing a sulfur or nitrogen atom cannot be configured in three dimensions as the L3 ligand interferes with such a configuration. In the tetramer type, three bonds extend from X. Thus, a halogen atom binds to those bonds to form a coordination structure, but a nitrogen or sulfur atom or an atomic group cannot bind to those bonds.

Concretely, the compounds classified in the above dimer type 1 include copper coordination compounds having any of the partial structural formulae represented by the following general formulae (2) and (3).

##STR00011##

In the formula (2), Cu represents a copper ion; X represents an atomic group containing a halogen, sulfur, or nitrogen atom; N represents a nitrogen atom of an imine group in a cyclic group; and at least one of A1 to A3 is a ligand composed of an atomic group containing a carbon atom and may be covalently bound to another one.

##STR00012##

In the formula (3), Cu represents a copper ion; X represents an atomic group containing a halogen, sulfur, or nitrogen atom; P represents a phosphorus atom in a phosphine compound; R₁ to R₃ independently or identically represent a linear, branched, or cyclic alkyl group or an aromatic ring group which may have a substituent; and at least one of A1 to A3 is a ligand composed of an atomic group containing a carbon atom and may be covalently bound to another one.

In addition, concretely, the compounds classified in the above dimer type 2 include copper coordination compounds having any of the partial structural formulae represented by the following general formulae (4-1) to (4-5).

##STR00013##

In the above formulae (4-1) to (4-5), Cu represents a copper ion; X represents an atomic group containing a halogen, sulfur, or nitrogen atom; and N—N, P—N, and P—P represent bidentate ligands in which each ligand has two coordinating atoms, where N—N contains two nitrogen atoms of an imine group, P—N contains one nitrogen atom of the imine group and one phosphorous atom, and P—P contains two phosphorous atoms.

In addition, concretely, the compounds classified in the above dimer type 3 include copper coordination compounds having any of the partial structural formulae represented by the following general formulae (5-1) to (5-3).

##STR00014##

In the formulae (5-1) to (5-3), Cu represents a copper ion; X represents a halogen atom; N represents a nitrogen atom in an imine group; and P represents a phosphorus atom; N—N, P—N, and P—P represent multidentate ligands in which each ligand has two or more coordinating atoms, where N—N contains two nitrogen atoms of the imine group, P—N contains one nitrogen atom of the imine group and one phosphorous atom, and P—P contains two phosphorous atoms.

Furthermore, concretely, the compounds classified in the above tetramer type include copper coordination compounds having any of the partial structural formulae represented by the following general formulae (7) and (8), in which A1 and A2 each represent a ligand composed of an atomic group containing a carbon atom.

##STR00015##

In the formula (7), Cu represents a copper ion; X represents a halogen atom; and N represents a nitrogen atom of an imine group in a cyclic group.

##STR00016##

In the formula (8), Cu represents a copper ion; X represents a halogen atom; P represents a phosphorus atom in a phosphine compound; and R¹ to R³ independently or identically represent a linear, branched, or cyclic alkyl group or an aromatic ring group which may have a substituent.

The ligand in the partial structural formula represented by each of the above general formulae (1) to (8) will be now described.

(1) Basic structural examples of an N—N ligand will be listed below.

##STR00017## ##STR00018## ##STR00019## ##STR00020##

In the present invention, the N—N-ligand can be used without modification or after the addition of a substituent on the above structural formula. Each of the above basic structures may contain a condensed ring group or a substituent. The substituent may be a halogen atom, a linear, branched, or cyclic alkyl group, or an aromatic group which may have a substituent. A CH₂ group of the alkyl group may be substituted with —O— or —NR— (wherein R is an alkyl group or an aromatic ring group which may be substituted), and an H atom may be substituted with an aromatic ring group or a halogen atom.

The above N—N ligand contains two imine groups. Now, examples of ligands having substituents on their basic skeletons will be listed below.

##STR00021## ##STR00022## ##STR00023## ##STR00024##

(2) Examples of the basic configuration of the P—N ligand will be listed below. The ligand contains one imine group and one phosphorus atom.

##STR00025## ##STR00026##

(3) Examples of the basic configuration of the P—P ligand will be listed below. The ligand contains two phosphorus atoms. In addition, the P—P ligand may have the same substituent as that of the N—N ligand mentioned in (1).

##STR00027##

(4) Examples of an R³R²R¹P ligand (monodentate ligand having one phosphorous atom) will be listed below.

##STR00028## ##STR00029## ##STR00030## ##STR00031## ##STR00032##

(5) Examples of a monodentate ligand having one nitrogen atom of an imine group in a cyclic group will be listed below.

##STR00033##

Furthermore, a high-molecular copper coordination compound as described below may be used in the present invention. In each of the following structural formulae, R represents one of alkyl, phenyl, aralkyl, and alkoxy groups.

##STR00034##

The high-molecular copper coordination compounds has a ligand having two imine groups in one molecule. In the formulae, X represents an atomic group containing a halogen, sulfur, or nitrogen atom. In the present invention, the high-molecular copper coordination compound refers to one having an average molecular weight of 3,000 or more. The high-molecular copper coordination compound may be suitably applied to a method in which such a compound is dissolved in a solvent and then subjected to the formation of a thin film by means of a spin coat method, inkjet method, or the like.

Furthermore, in the present invention, examples of the copper coordination compound where an atomic group containing a sulfur atom or a nitrogen atom as X of the dimer type 1 or 2 will be described below. In the following examples, the atomic group containing a nitrogen atom is a bidentate ligand containing a coordinate nitrogen atom. In the following structural formulae, Ph represents a phenyl group.

##STR00035## ##STR00036##

The copper coordination compound preferably used in the present invention is a non-ionic copper coordination compound which is electrically neutral. Thus, an ionic copper coordination compound requires a counter anion to be paired therewith. If they are employed in an organic EL device, they often hinder charge transport.

The configuration of the copper coordination compound can be determined using X-ray structure analysis.

The minimum excitation state of luminescence of the copper coordination compound to be used in the present invention may be one of the three different types described below, or may be a combined state thereof.

MLCT (metal-to-ligand-charge-transfer) excitation state

CC (cluster canter) excitation state

• • XLCT (halogen-to-ligand-charge-transfer) excitation state.

The contents of the excitation states are described in detail in Chemical Review, 1999, 99 p. 3625-3647. Even though it is difficult to specify each excitation state on each coordination compound, strong luminescence can be determined from the excitation state of the luminescence.

For attaining high luminescence efficiency, it is important to make the configuration of a ligand so as to prevent structural variations between the ground state and the excitation state. The coordination structure of Cu(I) is a pseudo-tetrahedral configuration having four coordination linkages. Higher luminescence is attained when the tetrahedral structure in the ground state is kept in the excitation state. For example, a phenanthroline ligand having two alkyl groups substituted at the positions 2 and 9 (N—N ligand having the chemical formulae 11: 301-308) has an advantage of retaining a pseudo-tetrahedral structure in the ground state even in the excitation state, thereby obtaining high luminescence property. Similarly in the case of a ligand having a pyridine ring, luminescence can be obtained more strongly when a hydrogen atom adjacent to a nitrogen atom is substituted with an alkyl group or the like. The tetrahedral structure, which tends to become a planar structure in the excitation state, retains a generally tetrahedral structure even in the excitation state by substituting with a bulky substituent.

The same holds true for a P—N ligand or P—P ligand, which contains a phosphorous atom, represented by the chemical formulae 12 or 13. In particular, an aromatic ring group bound to a phosphorous atom (for example, a phenyl, pyridine, or thienyl group) is very bulky, so that it will be effective in preventing flattening in the excitation manner.

In the copper coordination compound of the present invention, the above structural variations can be prevented in a solid rather than a solution, so that the copper coordination compound may provide strong luminescence. This is one of the reasons that the copper coordination compound in a solid state generates luminescence well.

Another reason is that the formation of an additional coordination structure occurs in a solution and the resulting structure may have the coordination number 5 which do not generate strong luminescence. Such a reaction of attaining the coordination number 5 is hardly obtained as a molecular movement is being restricted in a solid. Therefore, strong luminescence can be generated in a solid.

In addition, the powder solid of the copper coordination compound of the present invention has a luminescence lifetime of 0.05 to 50 μsec.

An aluminum quinolinol derivative, coumarin derivative, quinacridone derivative, or the like used until now allows the generation of very strong luminescence and retains its strong luminescence property in a solid dispersion without modification. This property also acts effectively in an organic EL device, thereby attaining high luminescence efficiency of the organic EL device.

However, the copper coordination compound used in the present invention shows very strong luminescence in a solid, compared with luminescence in a solution. The inventors of the present invention have considered the property of the copper coordination compound and found out that the copper coordination compound is useful as a light-emitting material of an organic EL device with high luminescence efficiency and stable luminescence.

The copper coordination compound used in the present invention is useful as a light-emitting material of an organic EL device. To say nothing of having high luminescence efficiency, the copper coordination compound is suitable for various kinds of coating methods including: a vacuum deposition process; a spin coat process in which the compound is prepared as a solution and then applied to; and a coating process with inkjet nozzles. Therefore, an organic EL device can be formed without causing any damage such as decomposition in a device production process.

Hereinafter, concrete examples of the copper coordination compound used in the present invention will be described.

TABLE 1
Dimer type 2
	Exemplified
	compound
	No.	L1	L2	X
	1001	301	301	I
	1002	302	302	I
	1003	303	303	I
	1004	304	304	I
	1005	305	305	I
	1006	306	306	I
	1007	307	307	I
	1008	308	308	I
	1009	309	309	I
	1010	310	310	I
	1011	311	311	I
	1012	312	312	I
	1013	313	313	I
	1014	314	314	I
	1015	315	315	I
	1016	316	316	I
	1017	317	317	I
	1018	318	318	I
	1019	401	401	I
	1020	402	402	I
	1021	403	403	I
	1022	404	404	I
	1023	405	405	I
	1024	406	406	I
	1025	407	407	I
	1026	408	408	I
	1027	409	409	I
	1028	410	410	I
	1029	411	411	I
	1030	412	412	I
	1031	501	501	I
	1032	502	502	I
	1033	503	503	I
	1034	504	504	I
	1035	505	505	I
	1036	506	506	I
	1037	301	403	I
	1038	302	403	I
	1039	303	403	I
	1040	304	403	I
	1041	305	403	I
	1042	306	403	I
	1043	307	403	I
	1044	308	403	I
	1045	309	403	I
	1046	310	403	I
	1047	311	403	I
	1048	312	403	I
	1049	313	403	I
	1050	314	403	I
	1051	315	403	I
	1052	316	403	I
	1053	317	403	I
	1054	318	403	I
	1055	401	403	I
	1056	402	403	I
	1057	403	403	I
	1058	404	403	I
	1059	405	403	I
	1060	406	403	I
	1061	407	403	I
	1062	408	403	I
	1063	409	403	I
	1064	410	403	I
	1065	411	403	I
	1066	412	403	I
	1067	301	503	I
	1068	302	503	I
	1069	303	503	I
	1070	304	503	I
	1071	305	503	I
	1072	306	503	I
	1073	307	503	I
	1074	308	503	I
	1075	309	503	I
	1076	310	503	I
	1077	311	503	I
	1078	312	503	I
	1079	313	503	I
	1080	314	503	I
	1081	315	503	I
	1082	316	503	I
	1083	317	503	I
	1084	318	503	I
	1085	401	503	I
	1086	402	503	I
	1087	403	503	I
	1088	404	503	I
	1089	405	503	I
	1090	406	503	I
	1091	407	503	I
	1092	408	503	I
	1093	409	503	I
	1094	410	503	I
	1095	411	503	I
	1096	412	503	I
	1097	301	504	I
	1098	302	504	I
	1099	303	504	I
	1100	304	504	I
	1101	305	504	I
	1102	306	504	I
	1103	307	504	I
	1104	308	504	I
	1105	309	504	I
	1106	310	504	I
	1107	311	504	I
	1108	312	504	I
	1109	313	504	I
	1110	314	504	I
	1111	315	504	I
	1112	316	504	I
	1113	317	504	I
	1114	318	504	I
	1115	401	504	I
	1116	402	504	I
	1117	403	504	I
	1118	404	504	I
	1119	405	504	I
	1120	406	504	I
	1121	407	504	I
	1122	408	504	I
	1123	409	504	I
	1124	410	504	I
	1125	411	504	I
	1126	412	504	I
	1127	301	301	Br
	1128	302	302	Br
	1129	303	303	Br
	1130	304	304	Br
	1131	305	305	Br
	1132	306	306	Br
	1133	307	307	Br
	1134	308	308	Br
	1135	309	309	Br
	1136	310	310	Br
	1137	311	311	Br
	1138	312	312	Br
	1139	313	313	Br
	1140	314	314	Br
	1141	315	315	Br
	1142	316	316	Br
	1143	317	317	Br
	1144	318	318	Br
	1145	401	401	Br
	1146	402	402	Br
	1147	403	403	Br
	1148	404	404	Br
	1149	405	405	Br
	1150	406	406	Br
	1151	407	407	Br
	1152	408	408	Br
	1153	409	409	Br
	1154	410	410	Br
	1155	411	411	Br
	1156	412	412	Br
	1157	501	501	Br
	1158	502	502	Br
	1159	503	503	Br
	1160	504	504	Br
	1161	505	505	Br
	1162	506	506	Br
	1163	301	403	Br
	1164	302	403	Br
	1165	303	403	Br
	1166	304	403	Br
	1167	305	403	Br
	1168	306	403	Br
	1169	307	403	Br
	1170	308	403	Br
	1171	309	403	Br
	1172	310	403	Br
	1173	311	403	Br
	1174	312	403	Br
	1175	313	403	Br
	1176	314	403	Br
	1177	315	403	Br
	1178	316	403	Br
	1179	317	403	Br
	1180	318	403	Br
	1181	401	403	Br
	1182	402	403	Br
	1183	403	403	Br
	1184	404	403	Br
	1185	405	403	Br
	1186	406	403	Br
	1187	407	403	Br
	1188	408	403	Br
	1189	409	403	Br
	1190	410	403	Br
	1191	411	403	Br
	1192	412	403	Br
	1193	301	503	Br
	1194	302	503	Br
	1195	303	503	Br
	1196	304	503	Br
	1197	305	503	Br
	1198	306	503	Br
	1199	307	503	Br
	1200	308	503	Br
	1201	309	503	Br
	1202	310	503	Br
	1203	311	503	Br
	1204	312	503	Br
	1205	313	503	Br
	1206	314	503	Br
	1207	315	503	Br
	1208	316	503	Br
	1209	317	503	Br
	1210	318	503	Br
	1211	401	503	Br
	1212	402	503	Br
	1213	403	503	Br
	1214	404	503	Br
	1215	405	503	Br
	1216	406	503	Br
	1217	407	503	Br
	1218	408	503	Br
	1219	409	503	Br
	1220	410	503	Br
	1221	411	503	Br
	1222	412	503	Br
	1223	301	504	Br
	1224	302	504	Br
	1225	303	504	Br
	1226	304	504	Br
	1227	305	504	Br
	1228	306	504	Br
	1229	307	504	Br
	1230	308	504	Br
	1231	309	504	Br
	1232	310	504	Br
	1233	311	504	Br
	1234	312	504	Br
	1235	313	504	Br
	1236	314	504	Br
	1237	315	504	Br
	1238	316	504	Br
	1239	317	504	Br
	1240	318	504	Br
	1241	401	504	Br
	1242	402	504	Br
	1243	403	504	Br
	1244	404	504	Br
	1245	405	504	Br
	1246	406	504	Br
	1247	407	504	Br
	1248	408	504	Br
	1249	409	504	Br
	1250	410	504	Br
	1251	411	504	Br
	1252	412	504	Br
	1253	504	504	Cl

TABLE 2
Dimer type 1
	Exemplified
	compound
	No.	L1 = L3	L2 = L4	X
	2001	601	701	I
	2002	602	701	I
	2003	603	701	I
	2004	604	701	I
	2005	605	701	I
	2006	606	701	I
	2007	607	701	I
	2008	608	701	I
	2009	609	701	I
	2010	610	701	I
	2011	611	701	I
	2012	612	701	I
	2013	613	701	I
	2014	614	701	I
	2015	615	701	I
	2016	616	701	I
	2017	617	701	I
	2018	618	701	I
	2019	619	701	I
	2020	620	701	I
	2021	621	701	I
	2022	622	701	I
	2023	623	701	I
	2024	624	701	I
	2025	601	702	I
	2026	601	703	I
	2027	601	704	I
	2028	601	705	I
	2029	601	706	I
	2030	601	707	I
	2031	601	708	I
	2032	601	709	I
	2033	601	710	I
	2034	602	705	I
	2035	603	705	I
	2036	604	705	I
	2037	605	705	I
	2038	606	705	I
	2039	607	705	I
	2040	608	705	I
	2041	609	705	I
	2042	610	705	I
	2043	611	705	I
	2044	612	705	I
	2045	613	705	I
	2046	614	705	I
	2047	615	705	I
	2048	616	705	I
	2049	617	705	I
	2050	618	705	I
	2051	619	705	I
	2052	620	705	I
	2053	621	705	I
	2054	622	705	I
	2055	623	705	I
	2056	624	705	I

TABLE 3
Dimer type 3
Exemplified
compound
No.	L1 = L2	L3	X
3001	601	201	I
3002	602	201	I
3003	603	201	I
3004	604	201	I
3005	605	201	I
3006	606	201	I
3007	607	201	I
3008	608	201	I
3009	609	201	I
3010	610	201	I
3011	611	201	I
3012	612	201	I
3013	613	201	I
3014	614	201	I
3015	615	201	I
3016	616	201	I
3017	617	201	I
3018	618	201	I
3019	619	201	I
3020	620	201	I
3021	621	201	I
3022	622	201	I
3023	623	201	I
3024	624	201	I
3025	601	202	I
3026	602	202	I
3027	603	202	I
3028	604	202	I
3029	605	202	I
3030	606	202	I
3031	607	202	I
3032	608	202	I
3033	609	202	I
3034	610	202	I
3035	611	202	I
3036	612	202	I
3037	613	202	I
3038	614	202	I
3039	615	202	I
3040	616	202	I
3041	617	202	I
3042	618	202	I
3043	619	202	I
3044	620	202	I
3045	621	202	I
3046	622	202	I
3047	623	202	I
3048	624	202	I
3049	601	211	I
3050	602	211	I
3051	603	211	I
3052	604	211	I
3053	605	211	I
3054	606	211	I
3055	607	211	I
3056	608	211	I
3057	609	211	I
3058	610	211	I
3059	611	211	I
3060	612	211	I
3061	613	211	I
3062	614	211	I
3063	615	211	I
3064	616	211	I
3065	617	211	I
3066	618	211	I
3067	619	211	I
3068	620	211	I
3069	621	211	I
3070	622	211	I
3071	623	211	I
3072	624	211	I
3073	701	501	I
3074	702	501	I
3075	703	501	I
3076	704	501	I
3077	705	501	I
3078	706	501	I
3079	707	501	I
3080	708	501	I
3081	601	401	I
3082	602	401	I
3083	603	401	I
3084	604	401	I
3085	605	401	I
3086	606	401	I
3087	607	401	I
3088	608	401	I
3089	609	401	I
3090	610	401	I
3091	611	401	I
3092	612	401	I
3093	613	401	I
3094	614	401	I
3095	615	401	I
3096	616	401	I
3097	617	401	I
3098	618	401	I
3099	619	401	I
3100	620	401	I
3101	621	401	I
3102	622	401	I
3103	623	401	I
3104	624	401	I
3105	701	401	I
3106	702	401	I
3107	703	401	I
3108	704	401	I
3109	705	401	I
3110	706	401	I
3111	707	401	I
3112	708	401	I
3113	601	201	Br
3114	602	201	Br
3115	603	201	Br
3116	604	201	Br
3117	605	201	Br
3118	606	201	Br
3119	607	201	Br
3120	608	201	Br
3121	609	201	Br
3122	610	201	Br
3123	611	201	Br
3124	612	201	Br
3125	613	201	Br
3126	614	201	Br
3127	615	201	Br
3128	616	201	Br
3129	617	201	Br
3130	618	201	Br
3131	619	201	Br
3132	620	201	Br
3133	621	201	Br
3134	622	201	Br
3135	623	201	Br
3136	624	201	Br
3137	601	202	Br
3138	602	202	Br
3139	603	202	Br
3140	604	202	Br
3141	605	202	Br
3142	606	202	Br
3143	607	202	Br
3144	608	202	Br
3145	609	202	Br
3146	610	202	Br
3147	611	202	Br
3148	612	202	Br
3149	613	202	Br
3150	614	202	Br
3151	615	202	Br
3152	616	202	Br
3153	617	202	Br
3154	618	202	Br
3155	619	202	Br
3156	620	202	Br
3157	621	202	Br
3158	622	202	Br
3159	623	202	Br
3160	624	202	Br
3161	601	211	Br
3162	602	211	Br
3163	603	211	Br
3164	604	211	Br
3165	605	211	Br
3166	606	211	Br
3167	607	211	Br
3168	608	211	Br
3169	609	211	Br
3170	610	211	Br
3171	611	211	Br
3172	612	211	Br
3173	613	211	Br
3174	614	211	Br
3175	615	211	Br
3176	616	211	Br
3177	617	211	Br
3178	618	211	Br
3179	619	211	Br
3180	620	211	Br
3181	621	211	Br
3182	622	211	Br
3183	623	211	Br
3184	624	211	Br
3185	701	501	Br
3186	702	501	Br
3187	703	501	Br
3188	704	501	Br
3189	705	501	Br
3190	706	501	Br
3191	707	501	Br
3192	708	501	Br
3193	601	401	Br
3194	602	401	Br
3195	603	401	Br
3196	604	401	Br
3197	605	401	Br
3198	606	401	Br
3199	607	401	Br
3200	608	401	Br
3201	609	401	Br
3202	610	401	Br
3203	611	401	Br
3204	612	401	Br
3205	613	401	Br
3206	614	401	Br
3207	615	401	Br
3208	616	401	Br
3209	617	401	Br
3210	618	401	Br
3211	619	401	Br
3212	620	401	Br
3213	621	401	Br
3214	622	401	Br
3215	623	401	Br
3216	624	401	Br
3217	701	401	Br
3218	702	401	Br
3219	703	401	Br
3220	704	401	Br
3221	705	401	Br
3222	706	401	Br
3223	707	401	Br
3224	708	401	Br
3225	601	201	Cl
3226	602	201	Cl
3227	603	201	Cl
3228	604	201	Cl
3229	605	201	Cl
3230	606	201	Cl
3231	607	201	Cl
3232	608	201	Cl
3233	609	201	Cl
3234	610	201	Cl
3235	611	201	Cl
3236	612	201	Cl
3244	620	201	Cl
3245	621	201	Cl
3246	622	201	Cl
3247	623	201	Cl
3248	624	201	Cl
3249	601	202	Cl
3250	602	202	Cl
3251	603	202	Cl
3252	604	202	Cl
3253	605	202	Cl
3262	614	202	Cl
3263	615	202	Cl
3264	616	202	Cl
3265	617	202	Cl
3266	618	202	Cl
3267	619	202	Cl
3268	620	202	Cl
3269	621	202	Cl
3270	622	202	Cl
3271	623	202	Cl
3272	624	202	Cl
3273	601	211	Cl
3274	602	211	Cl
3275	603	211	Cl
3276	604	211	Cl
3277	605	211	Cl
3278	606	211	Cl
3279	607	211	Cl
3280	608	211	Cl
3281	609	211	Cl
3282	610	211	Cl
3283	611	211	Cl
3284	612	211	Cl
3285	613	211	Cl
3286	614	211	Cl
3287	615	211	Cl
3288	616	211	Cl
3289	617	211	Cl
3290	618	211	Cl
3291	619	211	Cl
3292	620	211	Cl
3293	621	211	Cl
3294	622	211	Cl
3295	623	211	Cl
3296	624	211	Cl
3297	701	501	Cl
3298	702	501	Cl
3299	703	501	Cl
3300	704	501	Cl
3301	705	501	Cl
3302	706	501	Cl
3303	707	501	Cl
3304	708	501	Cl
3305	601	401	Cl
3306	602	401	Cl
3307	603	401	Cl
3308	604	401	Cl
3309	605	401	Cl
3310	606	401	Cl
3311	607	401	Cl
3312	608	401	Cl
3313	609	401	Cl
3315	611	401	Cl
3316	612	401	Cl
3317	613	401	Cl
3318	614	401	Cl
3319	615	401	Cl
3320	616	401	Cl
3321	617	401	Cl
3322	618	401	Cl
3323	619	401	Cl
3324	620	401	Cl
3325	621	401	Cl

TABLE 4
Tetramer type
	Exemplified
	compound
	No.	L1 = L2 = L3 = L4	X
	4001	601	I
	4002	602	I
	4003	603	I
	4004	604	I
	4005	605	I
	4006	606	I
	4007	607	I
	4008	608	I
	4009	609	I
	4010	610	I
	4011	611	I
	4012	612	I
	4013	613	I
	4014	614	I
	4015	615	I
	4016	616	I
	4017	617	I
	4018	618	I
	4019	619	I
	4020	620	I
	4021	621	I
	4022	622	I
	4023	623	I
	4024	624	I
	4025	701	I
	4026	702	I
	4027	703	I
	4028	704	I
	4029	705	I
	4030	706	I
	4031	707	I
	4032	708	I
	4033	601	Br
	4034	602	Br
	4035	603	Br
	4036	604	Br
	4037	605	Br
	4038	606	Br
	4039	607	Br
	4040	608	Br
	4041	609	Br
	4042	610	Br
	4043	611	Br
	4044	612	Br
	4045	613	Br
	4046	614	Br
	4047	615	Br
	4048	616	Br
	4049	617	Br
	4050	618	Br
	4051	619	Br
	4052	620	Br
	4053	621	Br
	4054	622	Br
	4055	623	Br
	4056	624	Br
	4057	701	Br
	4058	702	Br
	4059	703	Br
	4060	704	Br
	4061	705	Br
	4062	706	Br
	4063	707	Br
	4064	708	Br
	4065	601	Cl
	4066	602	Cl
	4067	603	Cl
	4068	604	Cl
	4069	605	Cl
	4070	606	Cl
	4071	607	Cl
	4072	608	Cl
	4073	609	Cl
	4074	610	Cl
	4075	611	Cl
	4076	612	Cl
	4077	613	Cl
	4078	614	Cl
	4079	615	Cl
	4080	616	Cl
	4081	617	Cl
	4082	618	Cl
	4083	619	Cl
	4084	620	Cl
	4085	621	Cl
	4086	622	Cl
	4087	623	Cl
	4088	624	Cl
	4089	701	Cl
	4090	702	Cl
	4091	703	Cl
	4092	704	Cl
	4093	705	Cl
	4094	706	Cl
	4095	707	Cl
	4096	708	Cl

A synthetic process of the metal coordination compound used in the present invention will be exemplified below.

##STR00037##

The reaction formulae (A) and (B) are synthetic processes for the dimer type 2 represented by the formulae 9. In the reaction formula (A), a metal coordination compound is prepared from the same type of ligands. In the reaction formula (B), on the other hand, a metal coordination compound is prepared from different ligands. Here, L, L¹, and L² represent bidentate ligands represented by the formulae 10 to 12, respectively, in each of which a nitrogen atom or a phosphorous atom is coordinated with a metal. In the formula, “Cu(μI)₂Cu” means a structure in which two copper atoms are crosslinked by two iodine atoms. For example, the binding form in which X in the dimer type 1 or 2 in the formulae 9 is replaced with an iodine atom will be shown. In a synthetic process, a copper iodide (1 mmol) is added to 20 ml of toluene or tetrahydrofuran. Then, a ligand is added to a mixture at a ratio represented in the reaction formula, followed by mixing and stirring. Subsequently, a reaction mixture is refluxed for 1 to 2 hours to complete the reaction. The resulting reaction solution is cooled down to the room temperature, whereby the precipitation of a target material is observed. Then, the precipitate is collected and washed with the same solvent as that of the reaction.

The reaction formula (C) is a synthetic process of the tetramer type represented by the formulae 9 and L in the formula is a monodentate ligand represented by the formulae 14 or 15. The reaction solvent or the like may be prepared by the same procedures represented in the reaction formulae (A) and (B) described above.

The reaction formula (D) is a synthetic process of the dimer type 1 represented by the formulae 9. The ligand L′ and CuBr are mixed in acetonitrile under stirring. Subsequently, the reaction product, the compound (a), is isolated through filtration and then added with another ligand L″ in the presence of chloroform, thereby obtaining the compound (b).

Next, the light-emitting device of the present invention will be described. The characteristic of the light-emitting device of the present invention is to contain the copper coordination compound described above as a light-emitting material in a light-emitting layer. In particular, the light-emitting layer preferably contains the copper coordination compound in a concentration of 100% by part.

The basic configuration of the organic EL device of the present invention is shown in FIGS. 1A to 1D, respectively. In the figures, reference numeral 1 denotes a metal electrode, 2 denotes a light-emitting layer, 3 denotes a hole transporting layer, 4 denotes a transparent electrode, 5 denotes a transparent substrate, and 6 denotes an electron transporting layer.

As shown in FIGS. 1A to 1D, in general, an organic EL device is prepared by stacking a layered structure, in which a single organic layer or plural organic layers is/are sandwiched between the transparent electrode 4 and the metal electrode 1, on the transparent substrate 5.

FIG. 1A shows the simplest configuration of the organic EL device, where the organic layer is constructed only of the light-emitting layer 2. In FIG. 1B and FIG. 1C, the organic layer is composed of two layers: the light-emitting layer 2 and the hole transporting layer 3 and the light-emitting layer 2 and the charge transporting layer 6, respectively. In FIG. 1D, the organic layer is composed of three layers: the hole transporting layer 3, the light-emitting layer 2, and the charge transporting layer 6.

An aluminum quinolinol complex or the like (a typical example thereof is Alq shown below) having charge transporting property and luminescence property is used for the light-emitting layer 2. For example, a triphenylamine derivative (a typical example thereof is α-NPD shown below) is mainly used for the hole transporting layer 3. Alternatively, the hole transporting layer 3 may be made of a polymer such as PVK, which has hole transporting property and shows blue EL luminescence itself. An oxadiazole derivative or the like, or Alq, Bphen, or BCP shown below may be used for the charge transporting layer 6.

##STR00038##

EXAMPLES 1 to 9

The following compounds were prepared according the reaction formulae (A) to (C), respectively. Also, the constructions of the respective compounds were identified through ¹H-NMR (Bruker DPX-400NMR) and elemental analysis (Vario EL CHNOS). In the elemental analysis, the measured value of the element weight ratio of CHN was in good agreement to the calculated value of the element weight ratio of CHN within 0.5% or less error.

In addition, the luminescence property of each compound was measured by means of photoexcitation. Luminescence spectra were measured using F4500 manufactured by Hitachi Instruments Service Co., Ltd. (excitation wavelengths from 350 to 450 nm). All measurements were done in the solid powder state. Luminescent colors ranged from blue green to red. The results of the measurement on luminescence spectrum are listed in Table 5 below.

TABLE 5
		Luminescence
	Exemplified	wavelength of
Examples	compound No.	solid powder	Half band width
1	1001	636 nm	—
2	1002	632 nm	109 nm
3	1035	480 nm	98 nm
4	1038	506 nm	78 nm
5	1098	629 nm	155 nm
6	1068	649 nm	121 nm
7	4001	540 nm	—
8	4005	536 nm	—
9	4025	580 nm	—

In the Table 1, “-” corresponds to a half band width of 100 to 150 nm.

The luminescence spectra of the exemplified compounds 1002, 1138, and 4005 used in Examples 2, 4, and 8 were shown as examples of the luminescence spectra in FIGS. 2A to 2C, respectively. All of them generate luminescence well in the solid state, so that they can be stable compounds under general circumferences at ordinary temperatures.

EXAMPLES 10 to 12

Organic EL devices were prepared using as light-emitting materials the exemplified compounds 1002, 1138, and 4005 synthesized in Examples 2, 4, and 8, respectively.

The configuration of a device having three organic layers shown in FIG. 1D was employed as a configuration of the organic EL device. More specifically, on a glass substrate (i.e., the transparent substrate 5), ITO (transparent electrode 4) of 100 nm in thickness was patterned so as to have an electrode area of 3.14 mm².

On the ITO substrate, PEDOT (for organic EL) manufactured by Bayer AG was applied in 40 nm in film thickness by means of spin coating at a speed of 1,000 rpm (20 seconds). Then, the resulting coating was dried at 120° C. for 1 hour in a vacuum chamber. On the resulting layered product, subsequently, a solution, which contained 10 g of chlorobenzene, 92 mg of polyvinyl carbazole (an average molecular weight of 9,600), and 8 mg of the exemplified compound 1002, 1138, or 4005, was applied by means of a spin coating at 2,000 rpm for 20 sec under nitrogen atmosphere, thereby obtaining an organic film (light emitting layer 2) of 50 nm in thickness.

After the film formation, the substrate was dried under the same condition as that of the film formation of PEDOT. The substrate was then mounted on a vacuum deposition chamber to form a Bphen film of 40 nm in film thickness by means of vacuum deposition. Therefore, the resulting organic layer had a total film thickness of 130 nm.

Subsequently, a cathode (metal electrode 1) having the following composition was formed:

Metal electrode layer 1 (15 nm): AlLi alloy (Li content of 1.8% by mass); and

Metal electrode 2 (100 nm): Al.

After completion of the film formation, the device was removed and evaluations were then conducted.

The properties of the device were evaluated by applying a DC voltage while making the metal electrode 1 negative and the transparent electrode 4 positive.

The voltage-current property of the organic layer showed good rectification property. The emission spectrum and luminescence intensity were measured using spectrum analyzers SR1 and BM7, manufactured by Topcon Corp. The current value at the time of voltage application was measured by 4140Bd manufactured by Hewlett-Packard. The luminescence efficiency was calculated from the luminescence intensity and the measured current value. For EL luminescence, good luminescence was observed at a luminescence of 200 cd/cm² and good luminescence was retained even after 10 hours of current application. The results are shown in Table 6.

EXAMPLE 13

A light-emitting device was prepared by the same way as that of Example 12, except for a light-emitting layer. In this example, the light-emitting layer was prepared in a film thickness of 30 nm using 100% by mass of the exemplified compound 4005 by means of spin coating. For EL luminescence, good luminescence was observed at a luminescence of 200 cd/cm² and good luminescence was retained even after 10 hours of current application. Therefore, it was found that the light-emitting device with higher luminescence efficiency than that of Example 12 can be attained by the formation of a light-emitting layer with 100% content of the exemplified compound 4005. The results are shown in Table 6.

EXAMPLE 14

In this example, all organic layers were prepared using a vacuum deposition process to complete an organic EL device. The material of the hole transporting layer 3 was α-NPD and the material of the light-emitting layer 2 was the exemplified compound 1002 synthesized in Example 2 in content of 100% by mass. In addition, the material of the charge transporting layer 6 was BPhen. Each of those layers was 40 nm in thickness.

The electro-optical property of the light-emitting device of this example was measured to show that a peak luminescence wavelength was 642 nm at the time of 10 V application. At this time, the light-emitting device had a luminescence efficiency of 0.8 cd/A, resulting in stable luminescence. Therefore, it was found that the light-emitting device with higher luminescence efficiency than that of Example 10 can be attained by the formation of a light-emitting layer with 100% content of the exemplified compound 1002. The results are shown in Table 6.

TABLE 6
					Current
					value at
	No. of				the time of
	exemplified		EL	Luminescence	8 V
	compound	Light-	luminescence	efficiency	application
Examples	used	emitting layer	wavelength	(cd/A)	(mA/cm2)
10	1002	1002 of 8% by	640 nm	0.5	41
		mass in PVK
11	1138	1138 of 8% by	520 nm	2.2	11
		mass in PVK
12	4005	4005 of 8% by	550 nm	2.8	9
		mass in PVK
13	4005	4005 of 100%	565 nm	4.1	61
		by mass
14	1002	1002 of 100%	642 nm	0.8	25
		by mass

EXAMPLES 15 to 17

Each of these examples is an example of a two-nuclei metal coordination compound (exemplified compound 1034, 1160, or 1253) using a ligand 504 represented in the formulae 13 as a bidentate ligand. Among the examples of the synthetic process of the metal coordination compound to be used in the present invention, the process of the reaction formula (A) was used to synthesize a desired compound. The synthesized compounds were excellent in thermal stability and had subliming property, so that each of them was purified by sublimation purification under a vacuum pressure of 10⁻¹ Pa. The identification of the compound was performed using element analysis and X-ray crystal analysis. The element analysis was conducted using an element analyzer Vario EL CHNOS (manufactured by Elementar Co., Ltd.). The X-ray crystal analysis was performed using crystals formed at the time of sublimation purification and a RAXIS RAPID imaging plate (manufactured by Rigakusha). In this case, X ray used was a MoKα ray (λ=0.71069 Å) which was converted into monochrome color though a graphite monochromator. The molecular structure as a result of crystal analysis on the exemplified compound 1253 was shown in FIG. 4.

Furthermore, the peak luminescence wavelength of the luminescence spectrum in the solid powder state and the luminescence lifetime are shown in FIG. 3. In the figure, from the left side, the curves correspond to the luminescence spectra of the exemplified compounds 1034, 1160, and 1253, respectively.

TABLE 7
		Luminescence	Luminescence
	Exemplified	wavelength	lifetime
Example No.	compound No.	nm	μsec
15	1034	502	3.9
16	1160	518	4.2
17	1253	533	4.3

As described above, the exemplified compounds 1034, 1160, and 1253 are excellent in thermal stability and are capable of generating strong luminescence at wavelength regions from green to yellow green in the solid states.

EXAMPLES 18 to 21

In these examples, organic LED devices were prepared using the exemplified compounds 1034 and 1253 synthesized in Examples 15 and 17 by means of a vacuum deposition process. The device configuration employed a compound represented by the formulae 19. In other words, the configuration was “NPD (50 nm)/CBP: Cu coordination compound (10%) (20 nm, 60 nm)/Bphen (40 nm)”. For an electrode, ITO was used on the NPD side, while Al was used on the Bphen side. In addition, 5 nm of potassium fluoride (KF) was layered as an electron injection layer between the Bphen and Al electrodes. For the light-emitting layer, the devices were prepared respectively using two different films having thicknesses of 20 nm and 60 nm. The organic LED devices of the examples showed good rectification property. The data on current-voltage-current-brightness provides the following results. The luminescence spectra of the examples showed longer wavelengths than those of the luminescence spectra in the solid state shown in Examples 15 and 17. In addition, it is also found that the wavelength is longer as the light-emitting layer is thicker.

TABLE 8
	Exempli-	Thickness	Power	Current	Lumi-
Exam-	fied	of light-	effi-	effi-	nescence
ple	compound	emitting	ciency	ciency	wave-
No.	No.	layer nm	lm/W	cd/A	length nm
18	1034	20	4.5	7	545
19	1034	60	2.1	6.4	565
20	1253	20	3.9	7.2	585
21	1253	60	0.4	5	600

Each of the copper coordination compounds of Examples 15 and 17 was used as a luminescence dopant in an organic LED device. Consequently, an organic LED device having high luminescence efficiency was obtained.

This application claims priority from Japanese Patent Application No. 2003-343157 filed on Oct. 1, 2003, and Japanese Patent Application No. 2004-267705 filed on Sep. 15, 2004, which are hereby incorporated by reference herein.

Claims

1. An organic light-emitting device comprising a pair of electrodes and, disposed between the pair of electrodes, a light-emitting layer including a copper coordination compound represented by the following formula:

2. The organic light-emitting device according to claim 1, wherein the N—N bidentate ligand is represented by one of formulae 201 through 219:

3. The organic light emitting device according to claim 1 further comprising a hole transporting layer between the pair of electrodes.

4. The organic light emitting device according to claim 1 further comprising an electron transporting layer between the pair of electrodes.

5. The organic light emitting device according to claim 1 further comprising a hole transporting layer and an electron transporting layer between the pair of electrodes.